1. Field of the Invention
The present invention relates to a magneto-optical playback method for reading out recorded information (magnetic domain) by utilizing the Kerr effect of magneto-optical recording interaction.
2. Description of the Prior Art
In a magneto-optical playback method which forms magnetic domains of recorded information bits in a magnetic layer of a magneto-optical recording medium and then irradiating the same with playback light such as semiconductor laser light to reproduce the recorded information by the magneto-optical interaction known as Kerr effect, it is necessary, for increasing the magneto-optical recording density, to shorten the bit length so as to dimensionally reduce the magnetic domains of information. In this case, the ordinary magneto-optical recording method known heretofore has such a disadvantage that, in ensuring a satisfactory signal-to-noise ratio during a playback mode, some restriction is unavoidable due to the laser wavelength of the playback light and the aperture of a lens.
Relative to the solution for the problem of a recording density restricted by the playback conditions, there is known an exemplary known technique of reproducing a signal from a recording medium, as disclosed in Japanese Patent Laid-open No. Hei 1 (1989)-14341 (corresponding to U.S. patent Ser. No. 07/278,011 filed Nov. 30, 1988, and European Patent Application laid open to public, EP A-0318925). In such reproducing method, recorded magnetic domains on a magnetic recording medium are extended by utilizing temperature rise derived from irradiation of laser light in a playback mode, to thereby achieve high-density signal reproduction beyond the aforementioned restriction relative to the recording density.
However, when such reproducing method is employed, there exists a problem with regard to improvement of the track density in the direction transverse to the tracks, although the linear density may be increased. More specifically, when the bit interval or the magnetic domain interval of recorded information bits is long, depending on the code data, extension of the magnetic domain in a playback mode is rendered great to consequently bring about another problem of crosstalk between the recorded magnetic domains on mutually adjacent tracks.